Abstract
We have measured the amount of fibroblast growth factor 1 (FGF-1) mRNA and protein in primary breast cancers and non-malignant breast tissue and have found greatly reduced levels in breast cancer compared with non-malignant tissue. A total of 116 breast cancers and 37 biopsies taken from non-malignant breast were compared for FGF-1 mRNA expression using reverse transcriptase-polymerase chain reaction (RT-PCR) and significantly lower levels were found in the cancer tissues (P < 0.001). These findings were confirmed at the protein level where four out of five breast cancers contained no detectable FGF-1 and a fifth cancer had a low level of FGF-1 compared with three samples from reduction mammoplasties. Similar results were obtained from breast cell lines in which 80% of cancer cell lines had very low levels of FGF-1, whereas all non-malignant breast cell lines contained higher levels of FGF-1. Immunohistochemical analysis indicated that FGF-1 was present in the luminal epithelial cells of the non-malignant breast but was absent from cancer cells. The decreased levels of FGF-1 in breast cancer may indicate that stimulation of cancer cells is resulting in down-regulation of FGF-1 expression or may implicate FGF-1 as a differentiation factor rather than a growth factor at its physiological concentration in the breast.
Highlights
The fibroblast growth factors (FGFs) form a family of nine identified growth regulatory proteins that share 35-50% overall homology and induce proliferation and differentiation of a wide range of cells of epithelial, mesodermal and neuroectodermal origin (Gospodarowicz et al, 1987; Burgess and Maciag, 1989; Klagsbrun, 1990; Goldfarb, 1990)
We have previously shown that FGF-1 and 2 are both present in human breast tissue (Gomm et al, 1991; Luqmani et al, 1992; Smith et al, 1994)
Eighteen cycles of polymerase chain reaction (PCR) were selected for estimation of actin levels and 28 cycles for FGF-1
Summary
The fibroblast growth factors (FGFs) form a family of nine identified growth regulatory proteins that share 35-50% overall homology and induce proliferation and differentiation of a wide range of cells of epithelial, mesodermal and neuroectodermal origin (Gospodarowicz et al, 1987; Burgess and Maciag, 1989; Klagsbrun, 1990; Goldfarb, 1990). Except FGF-1 and 2, are synthesised with an N-terminal hydrophobic signal sequence, enabling the classical mechanism of secretion from cells (Abraham et al, 1986; Jaye et al, 1986). Release of FGF-1 and 2 may occur through leakage from damaged cells or from viable cells through a novel mechanism (Mignatti et al, 1992; Cao and Pettersson, 1993). FGF-1 and 2 have both been reported to show nuclear as well as cytoplasmic localisation (Cao and Pettersson, 1993; Vijayan et al, 1993)
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